Cigarette smoking is responsible for over 400,000 (1 out of every 5) deaths in the United States each year. Most smokers are aware of the health consequences and want to quit, but have difficulty doing so. Only 3-5% of smokers who quit on their own are successful. Since the vast majority of those who attempt to quit will fail, the need for better approaches to smoking cessation is clear and urgent. A safe and effective means of blocking the effects of nicotine would be of considerable interest as a potential treatment for tobacco use. Vaccination to produce nicotine-specific antibodies may be viewed as an alternative method of blocking nicotine effects. Nicotine is a small molecule that does not elicit an immune response in animals of humans. In order for the immune system to respond to this hapten, nicotine can be combined or bound to a larger molecule in a unique manner so that an immune response is mounted against nicotine. Nabi Biopharmaceuticals has developed a conjugate vaccine (NicVAX) that consists of 3'-aminomethylnicotine bound to Pseudomonas aeruginosa exoprotein A, an exotoxin that has been made non-toxic by an amino acid deletion. Subjects will be randomized to one of four treatment groups.